The invention relates to a plate-type luminaire of the type known from EP 1 106 905 A2.
It is an object of the invention to achieve better all-round glare suppression for a luminaire.
A further object of the invention is to improve the efficiency of illumination.
The plate-type luminaire of the invention is intended to be of straightforward or simple design and of inexpensive configuration.
These objects are achieved according to the invention which relates to a plate-type luminaire. It comprises a prism plate made of translucent material. The prism plate has a smooth plate surface on one side and a prism surface on the opposite side of the plate. The prism surface comprises a multiplicity of mutually parallel, longitudinal ribs, which extend in a longitudinal direction of the plate and are formed in the prism plate.
The luminaire also comprises a cover plate made of translucent material, which has a smooth plate surface on both opposite sides. The cover plate rests on the prism surface of the prism plate by one of the smooth plate surfaces of the cover plate.
The luminaire further comprises an optical-waveguide plate, which has a smooth plate surface on both sides. It rests on the smooth plate surface of the prism plate by one of the smooth plate surfaces of the waveguide plate. The optical-waveguide plate has at least one end surface which is designed for introducing light from a light source into the optical-waveguide plate.
The plates are designed for transmitting light from the optical-waveguide plate through the prism plate and, from the latter, through the cover plate into a space adjacent to the cover plate. Furthermore, the prism plate, the cover plate and the optical-waveguide plate are located one upon the other, and are all curved continuously over most of their plate width in the same direction of curvature, which is transverse to the longitudinal direction of the longitudinal ribs of the prism plate. The longitudinal ribs are located on the inside of the arc of curvature of the prism plate.
It has been surprisingly found that the invention provides for both better glare suppression and better illumination efficiency. The plate-type luminaire of the invention is of straightforward and simple design, inexpensive to produce and operationally reliable.